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Oil and Water Experiment

This classic oil and water experiment is sometimes referred to as “fireworks in a jar” because it looks like fireworks falling down from the oil. Kids will love learning about density and how oil and water do not mix in this fun and easy science experiment!

RELATED: Fireworks in a Jar

This simple science experiment explores density using oil and water. Expand this further by mixing or trying other oils – does it act the same way? You can even use a pipette to add drops of colored water to oil in a jar or cup and observe what happens.

What is Density?

Density is the amount of mass per unit of volume. Let’s say you have two objects and they are the same size. If one object is heavier, then it is denser and if the other object is lighter, then it is less dense.

What you will see in this experiment is that oil is less dense than water, so it will float on top of the water.

The Science Behind It

Oil and water do not mix. Oil is less dense than water and floats on top of the water. Food coloring is water-based so it mixes with the water. When you add the food coloring to the oil it will not mix. Once you add the oil to the water, the food colored droplets start to drop down since they are heavier than the oil. Once they drop into the water they start to dissolve and look like tiny explosions (or fireworks).

Supplies Needed

• Vegetable Oil – we used canola oil
• Food Coloring
• A Clear Jar or Vase

Watch the Video Tutorial Here

1. Fill your jar or vase 3/4 full with water.

2. Add oil into a bowl. You do not need a lot like we used – you can even just use about 4 tablespoons of oil for a thin layer. A little more oil will show the difference in density slightly better for kids.

3. Add 4 -5 drops of food coloring for each color you want to add. We used green, blue and purple food coloring. You can use any colors you’d like but we would recommend no more than 3 as the colors will mix quickly and will make it harder to see them dropping down.

4. Whisk the food coloring into the oil. You can point out at this stage that you can already tell the oil and water will not mix.  It’s best to whisk and add the oil straight into the jar or vase before the food coloring settles on the bottom of the bowl or or it may not form droplets when you add it to the water.

5. Add the oil into the water.

Now wait and see all of the little drops start to come down from the oil (making “fireworks”).

We love how easy this simple science experiment is – and kids will love to observe or make their own fireworks in a jar too!

More Science Experiments for Kids

• Try this fun and easy Grow a Rainbow Experiment . You only need washable markers and paper towel!
• For another fun experiment, make some oobleck! 
• Try a rainbow rain cloud in the jar experiment!

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Related ideas:.

How to Make Slime With Contact Solution

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Mixing Oil & Water Science Experiment

Have you ever heard the saying, “Oil and water don’t mix”? For this easy science experiment, we observe exactly what does happens when we mix oil and water, then we’ll add another item to the mix to see how it changes!

With only a few common kitchen items, kids can explore density and the reaction of adding an emulsifier (dish soap) to the experiment. A printable instruction sheet with a materials list, demonstration video, and a simple scientific explanation are included.

JUMP TO SECTION: Instructions | Video Tutorial | How it Works

Supplies Needed

• Glass Jar with a lid (a pint canning jar works great)
• 1 cup Water
• Food Coloring
• 1 cup Oil (we used vegetable oil)
• 2 teaspoons Dish Soap

Mixing Oil & Water Science Lab Kit – Only $5

Use our easy Mixing Oil & Water Science Lab Kit to grab your students’ attention without the stress of planning!

It’s everything you need to  make science easy for teachers and fun for students  — using inexpensive materials you probably already have in your storage closet!

Mixing Oil & Water Science Experiment Instructions

Step 1 – Start by filling the jar with 1 cup of water.

Step 2 – Add a few drops of food coloring to the water and stir until combined. Make some observations about the water. What happened when the food coloring was added? Was it easy to mix the food coloring into the water? Does the food coloring stay mixed with the water? What do you think will happen when we pour the oil into the jar? Write down your hypothesis (prediction) and then follow the steps below.

Step 3 – Next pour 1 cup of oil into the jar. Make a few observations. Does the oil behave the same was as the food coloring did when you added it to the water?

Step 4 – Securely tighten the lid on the jar and shake it for 15-20 seconds.

Step 5 – Set the jar down and watch the jar for a couple of minutes. Observe what happens to the oil and the water and write down your findings. Did the oil and water stay mixed together? Was your hypothesis correct? Do you think there is anything else that can be added to the jar to prevent the oil and water from separating?

Step 6 – Next, take the lid off the jar and squirt in 1-2 teaspoons of dish soap.

Step 7 – Tighten the lid back on the jar and shake again for another 15-20 seconds.

Step 8 – Set the jar down and watch the liquid for a minute or two. Observe what happens to the oil and the water now that the dish soap has been added to the mix. Write down your findings. Did the oil and water stay mixed together this time? Do you know why adding the dish soap preventing the oil and water from separating? Find out the answer in the how does this experiment work section below.

Video Tutorial

How Does the Science Experiment Work

The first thing you will observe is that oil and water will not stay mixed together, no matter how hard you shake the jar. Instead, the oil slowly rises to the top of the water. This is because of the density of the two liquids. Density is a measure of the mass per unit volume of a substance. Water has a density of 1 g/mL (g/cm3). Objects will float in water if their density is less than 1 g/mL. Objects will sink in water if their density is greater than 1 g/mL. The oil is LESS dense than the water. This is because the molecules of oil are larger than the molecules of water, so oil particles take up more space per unit area. As a result, the oil will rise to the top of the water.

The second thing you will observe is that adding dish soap to the mixture changed the results of the experiment. When oil, water and dish soap are mixed together, the oil and water don’t separate like they did when they were the only two items in the jar. This is because of the chemistry of the oil, water and soap molecules.

Oil (and other fats) are made of nonpolar molecules, meaning they cannot dissolve in water. Water is made of polar molecules that can dissolve other polar molecules. Soap is made of molecules that have a hydrophilic (“water-loving”) end and a hydrophobic (“water-fearing”) end. Without soap, water and oil cannot interact because they are unlike molecules. When you add soap to the mixture, the hydrophobic end of the soap molecule breaks up the nonpolar oil molecules, and the hydrophilic end of the soap molecule links up with the polar water molecules. Now that the soap is connecting the fat and water, the non-polar fat molecules can be carried by the polar water molecules. Now the oil and water can be mixed together and stay mixed together!

I hope you enjoyed the experiment. Here are some printable instructions:

Mixing Oil & Water Science Experiment

• Glass Jar with a lid (a pint canning jar works great)

Instructions

• Start by filling the jar with 1 cup of water.
• Add a few drops of food coloring to the water and stir until combined.
• Pour 1 cup of Oil into the jar.
• Securely tighten the lid on the jar and shake it for 15-20 seconds.
• Set the jar down and watch the liquid for a minute or two. Observe what happens to the Oil and the Water.
• Next, take the lid off the jar and squirt in 1-2 teaspoons of dish soap.
• Tighten the lid back on the jar and shake again for another 15-20 seconds.
• Set the jar down and watch the liquid for a minute or two. Observe what happens to the Oil and the Water now that the dish soap has been added to the mix.

Reader Interactions

October 4, 2017 at 11:43 am

Super ….. !

October 6, 2017 at 12:12 pm

Hi ! This gives us really good experiment

November 6, 2017 at 3:40 pm

This was the best science fair project ever

November 14, 2017 at 5:10 pm

December 10, 2017 at 10:38 am

This experiment is fun

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Oil and Water Science Exploration

We’re definitely adding this oil and water science exploration to our growing list of science experiments for preschoolers . But even older kids will enjoy it too! So if you are looking for a quick and easy science exploration for kids, then you have to check this one out.

Plus, check out this list of our favorite science activities for kids.

My kids (4 and 6 years old) get really excited when I set up a science experiment for them and this activity didn’t disappoint. Who am I kidding? Any time they can squirt water with droppers, they are happy as a clam.

*Note: This experiment is meant to be done with adult supervision. You should always supervise children while doing it.

Totally Cool Oil and Water Science Experiment!

They actually did this oil and water science experiment several times on this particular day and are already talking about doing it again. They still LOVE our lava lamp science experiment best, but this one is definitely a keeper.

It is very simple to set up this activity. You only need a few supplies that you probably already have around the house.

Supplies Needed:

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• Baby oil or vegetable oil (depends on if you want it to be clear)
• Washable liquid watercolors or food coloring
• Pipettes or droppers

*If you decide to use baby oil and watercolors, make sure your kids won’t put this in their mouths! As always, keep a close eye on your kids any time that you are doing a science experiment.

• Put water in several cups and add food coloring or liquid watercolors to the water. Then stir to combine.
• Place a pipette in each colored glass of water.
• Fill a cup about half way with oil.

Now let the kids have fun exploring oil and water!

While enjoying this science exploration kids will explore how oil and water do not mix together. For young children, there is no need to fully explain the concept behind it, but it is a great start to simply explore the two liquids and see how they behave when mixed together.

For kids in early elementary you can explain that oil molecules are only attracted to other oil molecules and water molecules are attracted to water molecules. So they don’t mix together. The reason the oil floats on top is because the oil is less dense than water.

Check out some more oil and water science investigations!

Lava Lamp Science Experiment

Two Color Oil and Water Discovery Bottles from Play Trains

Ocean in a Bottle Sensory Bottle from Happy Hooligans

Benefits of Science Experiments for Kids

Science experiments help foster curiosity, ignite children’s imagination and help nurture a love for learning!

1. Hands-On Learning

When young kids actively engage in experiments, the tactile nature of experiments allows them to visualize abstract ideas, fostering comprehension that traditional teaching methods might struggle to achieve.

2. Cultivating Critical Thinking

Through engaging in science experiments, children refine their skills in observing, analyzing, and incorporating new information.

3. Fostering Creativity

When children witness unexpected outcomes, they are prompted to think creatively and to experiment with new strategies.

4. Building Confidence and Self-Esteem

The newfound confidence from successful results will have a positive ripple effect, encouraging them to tackle new challenges with enthusiasm.

5. Real-Life Application

Science experiments showcase how the principles are applied in real-world situations.

6. Improved Fine Motor Skills

Engagement in science experiments is a fun way for kids to work on fine motor skills.

7. Bonding and Collaborative Learning

Science experiments can become wonderful bonding experiences for families, friends, and classmates.

Science experiments offer amazing benefits for kids while being fun and engaging!

Here are some more of our favorite science experiments!

This oobleck recipe is so much fun for kids! You just need two ingredients and the correct ratios to make it!

If your kids love candy, they’ll really enjoy this Skittles rainbow science activity .

This magic pepper and soap  science experiment is fun and super easy to do! Add it to your  preschool  or kindergarten  science lesson  plans.

• April 13, 2020

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Purposeful play, oil and water science experiment, steam activity for kids.

We all know that oil and water do not mix-but do we know why? Do kids know why? This Oil and Water Science Activity is a fun and easy way for kids to explore polarity and gives kids a hands-on and safe way to explore science!

Food Coloring

Explores cause and effect

Experiment with the reaction of mixing oil and water

Experiment with coloring mixing

Screen Free Fun

Shop this project!

Step 1: Color water

Fill several jars or cups with water

Add food coloring to water

Step 2: oil

Add oil (any type of oil will do-I used baby oil) to a tray, pan or bowl.

Step 3: Add drops

Using pipettes or a straw-add droplets of colored water to the oil.

Step 4: Continue

Let your child continue to explore.

Explain the science behind the experiment to your child.

Be sure to introduce new words in your explanation. 

Why doesn't Water and oil Mix?

Water molecules are polar molecules-meaning they have equal and opposite charges.

Water molecules have one positively charged end and one negatively charged end and are attracted to each other and bond together. 

Oil on the other hands is non-polar and unable to mix with polar molecules. 

Non-polar molecules only mix well with other non-polar molecules.

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Oil and Water Experiment

Explore what happens when you mix oil and water, and food coloring and learn about liquid density. A simple oil and water science experiment for kids to enjoy! There are tons of ways to have fun with science all year round!

Grab this free printable information guide on density to add to your project. Plus, it also comes with our best science practice sheets to share. You can find more easy density experiments here !

• Food coloring
• Toy fish (optional)

Instructions:

STEP 1. Fill the small cups with water.

STEP 2. Add 2 to 3 drops of food coloring to each cup. Stir with spoon. Notice what happens to the food coloring.

STEP 3. Next  fill the larger cup with baby oil. You don’t need to fill it too full – halfway is fine.

STEP 4. Fill the dropper with the colored water. Slowly drop the colored water into the cup of oil and watch what happens! Add the toy fish for some fun play!

Extend the activity by adding additional color drops such as yellow and watch the colors mix! The c olors may start to mix at the bottom of the cup for a cool effect. 

💡 For older students, here’s a list of more oil and water experiments .

Oil and Water Experiment Explanation

Did you notice the oil and water separated even when you tried to mix them together? Oil and water don’t mix because they have different properties.

Water molecules are polar (they have a slight electric charge), while oil molecules are nonpolar. This causes them to stay separate, with oil floating on top because it’s less dense (or heavy) than water.

Food coloring is made of water-based dyes, so when you add drops to the oil and water mixture, the coloring sinks through the oil and only mixes with the water. This is because food coloring is polar like water, so it dissolves in water but not in oil.

💡 See here for a more detailed explanation of why oil and water don’t mix .

Explore More Oil and Water Experiments

Want to see how you can mix oil and water using an emulsifier? Check out our salad dressing activity.

How about a classic homemade lava lamp with oil, water, and alka seltzer tablets!

Making a density tower  is another great way to observe how not all liquids weigh the same.

💡 Explore more  density experiments  [here].

Printable Science Projects For Kids

If you’re looking to grab all of our printable science projects in one convenient place, plus exclusive worksheets and bonuses like a STEAM Project pack, our Science Project Pack is what you need! Over 300+ Pages!

• 90+ classic science activities  with journal pages, supply lists, set up and process, and science information.  NEW! Activity-specific observation pages!
• Best science practices posters  and our original science method process folders for extra alternatives!
• Be a Collector activities pack  introduces kids to the world of making collections through the eyes of a scientist. What will they collect first?
• Know the Words Science vocabulary pack  includes flashcards, crosswords, and word searches that illuminate keywords in the experiments!
• My science journal writing prompts  explore what it means to be a scientist!!
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